junction box in loft

[wrathkeg]

I am looking to put a junction box in an existing lighting circuit to run to new loft lights. A convenient place would be just above a light fitting in one of the bedrooms. The wiring at said light fitting looks like this.

In the loft, the wiring looks like this.

My question is, does it matter which black cable I connect at the junction box?

I've been a bit thrown by not finding T&E up there, and also difficulty following the wiring around the loft which is part boarded, and full of junk.

Thanks!

wrathkeg

 

[Simon35]

Can you not use the light fitting as the junction box. Just shove your cable down from the loft with the others.

That live (red) will only be live when the light is switched on, its not a permanent live.

The neutrals (black), you can connect to either.

 

[wrathkeg]

Thanks. I hadn't thought of using the light fitting as a junction box. To do that though I think I'd need to enlarge the hole in the noggin to get the new cable through so maybe not easier than a junction box. But possible.

If that's a switched live then presumably any new loft lights connected to it (either at a junction box or the light fitting) could only come on when that light was on as well?

 

[Taylortwocities]

If that's a switched live then presumably any new loft lights connected to it (either at a junction box or the light fitting) could only come on when that light was on as well?

Correct
If you want your loft light to be switched separately (like a switch in the loft hatch) then you cannot use that light rose. It only has a neutral and a switched live.
You need a permanent live and neutral. Follow those wires in the loft back. Hopepfully you'll find a junction box up there with permanent live and neutral that you can use.

 

[wrathkeg]

Thanks. I'll go back into the loft when I get the chance. In the meantime, I've checked the light fittings upstairs which are all accessible to a degree from the loft and they all seem to be the same as in the picture i.e. two neutrals and a switched live.

What would realistic options be for loft lights+switch if I can't find a permanent live?

 

[Simon35]

Thanks. I'll go back into the loft when I get the chance. In the meantime, I've checked the light fittings upstairs which are all accessible to a degree from the loft and they all seem to be the same as in the picture i.e. two neutrals and a switched live.

What would the options be for loft lights+switch if I can't find a permanent live?

Either finding a permanent live, or feed the loft lights from the switched live, and switch the upstairs lights on to illuminate the loft, which wouldn't be a major problem I would guess.

Disconnect, pull the wires up into the loft, make the noggin hole bigger, all wires back down, reconnect, job done.

 

[wrathkeg]

Thanks. I'd rather avoid having to switch the lights on downstairs for the lights in the loft to work if possible.

I will try to find a permanent live, but with the state of the loft, I'm not hopeful.

 

[ban-all-sheds]

In the loft, the wiring looks like this.

View attachment 126787

Well it shouldn't - it really really should not be exposed single cores like that. Either sheathed cable should be used or those wires should be in conduit.

If the wiring all through your chaotic loft is like that, i.e. it's not just a case that someone stripped a couple of bits of T&E back too far for that light, then you've got a bit of a risk up there...

 

[Simon35]

Well it shouldn't - it really really should not be exposed single cores like that. Either sheathed cable should be used or those wires should be in conduit.

If the wiring all through your chaotic loft is like that, i.e. it's not just a case that someone stripped a couple of bits of T&E back too far for that light, then you've got a bit of a risk up there...

I thought they looked like double insulated singles TBH

 

[Risteard]

They appear to be insulated and sheathed (not double insulated) with a sheath the same colour as the insulation. This is unusual though. The cpc will also be undersized due to not being mechanically protected or integral to a cable. (Should be minimum 4mm^2.) Realistically the only advice is to get the installation inspected and tested and a report on its condition obtained as prescribed by BS7671.

 

[JohnW2]

I thought they looked like double insulated singles TBH

They surely are, per the photo of the rose.

It seems to be a rather unusual wiring arrangement. It seems as if the neutral is probably looped between all the ceiling roses, each of which is supplied with just a switched live, the switches getting their permanent L from somewhere else. Is this common?

Kind Regards, John

 

[Taylortwocities]

Show us a picture of teh wiring behind the light switch in the same room as that ceiling rose.

That will eliminate the possibility of the loop in being at the switch.

As they are black and red "insulated and sheathed" (for the pedants) I would guess your house is of an age where there is a big junction box up in the loft somewhere. At that point there will be all the connections and supplies that you require.

As in my post above, you will probably find it if you follow the wires up in the loft to their origin.

 

[wrathkeg]

Picture attached. Incidentally, I have seen another switch on the same floor with one cable going to COM and another going to L1: there is no third one as in this picture.

I haven't seen any kind of junction box in there before, so if such a thing would be any kind of size, then I doubt there is one.

 

[Simon35]

They appear to be insulated and sheathed (not double insulated) with a sheath the same colour as the insulation. This is unusual though. The cpc will also be undersized due to not being mechanically protected or integral to a cable. (Should be minimum 4mm^2.) Realistically the only advice is to get the installation inspected and tested and a report on its condition obtained as prescribed by BS7671.

But if it was compliant with the regs at the time of installation then it's OK.

I'm not saying it was, I don't know the date of installation, and wouldn't have the appropriate copy of the regs for that date in any case.

But to say that the only advice is to get the whole installation inspected seems excessive IMHO.

 

[Taylortwocities]

The cables will be all together in a junction box, up there somewhere. Follow the wires in the loft, either from the ceiling rose, or from whre those wires from the switch come up into the loft. They WILL meet somewhere. Almost certainly up in the LOFT.
I will probably look a bit like this

Time to do some burying under all that itchy insulation, sorry!